Make color tables mutable

src/ImageSharp/Formats/Gif/GifDecoderCore.cs

@@ -716,7 +716,7 @@ internal sealed class GifDecoderCore : IImageDecoderInternals
                 colorTable[i] = new Color(Unsafe.Add(ref localBase, (uint)i));
             }
 
-            gifMeta.DecodedLocalColorTable = colorTable;
+            gifMeta.LocalColorTable = colorTable;
         }
 
         // Graphics control extensions is optional.
@@ -793,7 +793,7 @@ internal sealed class GifDecoderCore : IImageDecoderInternals
                     colorTable[i] = new Color(Unsafe.Add(ref globalBase, (uint)i));
                 }
 
-                this.gifMetadata.DecodedGlobalColorTable = colorTable;
+                this.gifMetadata.GlobalColorTable = colorTable;
             }
         }
     }

src/ImageSharp/Formats/Gif/GifEncoderCore.cs

@@ -102,10 +102,10 @@ internal sealed class GifEncoderCore : IImageEncoderInternals
         if (this.quantizer is null)
         {
             // Is this a gif with color information. If so use that, otherwise use octree.
-            if (gifMetadata.ColorTableMode == GifColorTableMode.Global && gifMetadata.DecodedGlobalColorTable.Length > 0)
+            if (gifMetadata.ColorTableMode == GifColorTableMode.Global && gifMetadata.GlobalColorTable?.Length > 0)
             {
                 // We avoid dithering by default to preserve the original colors.
-                this.quantizer = new PaletteQuantizer(gifMetadata.DecodedGlobalColorTable, new() { Dither = null });
+                this.quantizer = new PaletteQuantizer(gifMetadata.GlobalColorTable.Value, new() { Dither = null });
             }
             else
             {
@@ -234,11 +234,11 @@ internal sealed class GifEncoderCore : IImageEncoderInternals
             if (useLocal)
             {
                 // Reassign using the current frame and details.
-                if (metadata?.DecodedLocalColorTable.Length > 0)
+                if (metadata?.LocalColorTable?.Length > 0)
                 {
                     // We can use the color data from the decoded metadata here.
                     // We avoid dithering by default to preserve the original colors.
-                    PaletteQuantizer localQuantizer = new(metadata.DecodedLocalColorTable, new() { Dither = null });
+                    PaletteQuantizer localQuantizer = new(metadata.LocalColorTable.Value, new() { Dither = null });
                     using IQuantizer<TPixel> frameQuantizer = localQuantizer.CreatePixelSpecificQuantizer<TPixel>(this.configuration, localQuantizer.Options);
                     quantized = frameQuantizer.BuildPaletteAndQuantizeFrame(frame, frame.Bounds());
                 }

src/ImageSharp/Formats/Gif/GifFrameMetadata.cs

@@ -25,9 +25,9 @@ public class GifFrameMetadata : IDeepCloneable
         this.FrameDelay = other.FrameDelay;
         this.DisposalMethod = other.DisposalMethod;
 
-        if (other.DecodedLocalColorTable.Length > 0)
+        if (other.LocalColorTable?.Length > 0)
         {
-            this.DecodedLocalColorTable = other.DecodedLocalColorTable.ToArray();
+            this.LocalColorTable = other.LocalColorTable.Value.ToArray();
         }
 
         this.HasTransparency = other.HasTransparency;
@@ -40,9 +40,9 @@ public class GifFrameMetadata : IDeepCloneable
     public GifColorTableMode ColorTableMode { get; set; }
 
     /// <summary>
-    /// Gets the decoded global color table, if any.
+    /// Gets or sets the local color table, if any.
     /// </summary>
-    public ReadOnlyMemory<Color> DecodedLocalColorTable { get; internal set; }
+    public ReadOnlyMemory<Color>? LocalColorTable { get; set; }
 
     /// <summary>
     /// Gets or sets a value indicating whether the frame has transparency

src/ImageSharp/Formats/Gif/GifMetadata.cs

@@ -25,9 +25,9 @@ public class GifMetadata : IDeepCloneable
         this.ColorTableMode = other.ColorTableMode;
         this.BackgroundColor = other.BackgroundColor;
 
-        if (other.DecodedGlobalColorTable.Length > 0)
+        if (other.GlobalColorTable?.Length > 0)
         {
-            this.DecodedGlobalColorTable = other.DecodedGlobalColorTable.ToArray();
+            this.GlobalColorTable = other.GlobalColorTable.Value.ToArray();
         }
 
         for (int i = 0; i < other.Comments.Count; i++)
@@ -50,12 +50,12 @@ public class GifMetadata : IDeepCloneable
     public GifColorTableMode ColorTableMode { get; set; }
 
     /// <summary>
-    /// Gets the decoded global color table, if any.
+    /// Gets or sets the global color table, if any.
     /// </summary>
-    public ReadOnlyMemory<Color> DecodedGlobalColorTable { get; internal set; }
+    public ReadOnlyMemory<Color>? GlobalColorTable { get; set; }
 
     /// <summary>
-    /// Gets or sets the index at the <see cref="DecodedGlobalColorTable"/> for the background color.
+    /// Gets or sets the index at the <see cref="GlobalColorTable"/> for the background color.
     /// The background color is the color used for those pixels on the screen that are not covered by an image.
     /// </summary>
     public byte BackgroundColor { get; set; }

tests/ImageSharp.Tests/Formats/Gif/GifEncoderTests.cs

@@ -175,11 +175,11 @@ public class GifEncoderTests
         int maxColors;
         if (colorMode == GifColorTableMode.Global)
         {
-            maxColors = metaData.DecodedGlobalColorTable.Length;
+            maxColors = metaData.GlobalColorTable.Value.Length;
         }
         else
         {
-            maxColors = frameMetadata.DecodedLocalColorTable.Length;
+            maxColors = frameMetadata.LocalColorTable.Value.Length;
         }
 
         GifEncoder encoder = new()
@@ -201,11 +201,11 @@ public class GifEncoderTests
         colorMode = cloneMetadata.ColorTableMode;
         if (colorMode == GifColorTableMode.Global)
         {
-            maxColors = metaData.DecodedGlobalColorTable.Length;
+            maxColors = metaData.GlobalColorTable.Value.Length;
         }
         else
         {
-            maxColors = frameMetadata.DecodedLocalColorTable.Length;
+            maxColors = frameMetadata.LocalColorTable.Value.Length;
         }
 
         Assert.Equal(64, maxColors);
@@ -217,7 +217,7 @@ public class GifEncoderTests
 
             if (iMeta.ColorTableMode == GifColorTableMode.Local)
             {
-                Assert.Equal(iMeta.DecodedLocalColorTable.Length, cMeta.DecodedLocalColorTable.Length);
+                Assert.Equal(iMeta.LocalColorTable.Value.Length, cMeta.LocalColorTable.Value.Length);
             }
 
             Assert.Equal(iMeta.FrameDelay, cMeta.FrameDelay);

tests/ImageSharp.Tests/Formats/Gif/GifFrameMetadataTests.cs

@@ -15,18 +15,18 @@ public class GifFrameMetadataTests
         {
             FrameDelay = 1,
             DisposalMethod = GifDisposalMethod.RestoreToBackground,
-            DecodedLocalColorTable = new[] { Color.Black, Color.White }
+            LocalColorTable = new[] { Color.Black, Color.White }
         };
 
         GifFrameMetadata clone = (GifFrameMetadata)meta.DeepClone();
 
         clone.FrameDelay = 2;
         clone.DisposalMethod = GifDisposalMethod.RestoreToPrevious;
-        clone.DecodedLocalColorTable = new[] { Color.Black };
+        clone.LocalColorTable = new[] { Color.Black };
 
         Assert.False(meta.FrameDelay.Equals(clone.FrameDelay));
         Assert.False(meta.DisposalMethod.Equals(clone.DisposalMethod));
-        Assert.False(meta.DecodedLocalColorTable.Length == clone.DecodedLocalColorTable.Length);
+        Assert.False(meta.LocalColorTable.Value.Length == clone.LocalColorTable.Value.Length);
-        Assert.Equal(1, clone.DecodedLocalColorTable.Length);
+        Assert.Equal(1, clone.LocalColorTable.Value.Length);
     }
 }

tests/ImageSharp.Tests/Formats/Gif/GifMetadataTests.cs

@@ -34,7 +34,7 @@ public class GifMetadataTests
         {
             RepeatCount = 1,
             ColorTableMode = GifColorTableMode.Global,
-            DecodedGlobalColorTable = new[] { Color.Black, Color.White },
+            GlobalColorTable = new[] { Color.Black, Color.White },
             Comments = new List<string> { "Foo" }
         };
 
@@ -42,12 +42,12 @@ public class GifMetadataTests
 
         clone.RepeatCount = 2;
         clone.ColorTableMode = GifColorTableMode.Local;
-        clone.DecodedGlobalColorTable = new[] { Color.Black };
+        clone.GlobalColorTable = new[] { Color.Black };
 
         Assert.False(meta.RepeatCount.Equals(clone.RepeatCount));
         Assert.False(meta.ColorTableMode.Equals(clone.ColorTableMode));
-        Assert.False(meta.DecodedGlobalColorTable.Length == clone.DecodedGlobalColorTable.Length);
+        Assert.False(meta.GlobalColorTable.Value.Length == clone.GlobalColorTable.Value.Length);
-        Assert.Equal(1, clone.DecodedGlobalColorTable.Length);
+        Assert.Equal(1, clone.GlobalColorTable.Value.Length);
         Assert.False(meta.Comments.Equals(clone.Comments));
         Assert.True(meta.Comments.SequenceEqual(clone.Comments));
     }
@@ -208,7 +208,7 @@ public class GifMetadataTests
 
         if (colorTableMode == GifColorTableMode.Global)
         {
-            Assert.Equal(globalColorTableLength, gifMetadata.DecodedGlobalColorTable.Length);
+            Assert.Equal(globalColorTableLength, gifMetadata.GlobalColorTable.Value.Length);
         }
 
         Assert.Equal(frameDelay, gifFrameMetadata.FrameDelay);

tests/ImageSharp.Tests/Image/ImageFrameCollectionTests.NonGeneric.cs

@@ -318,7 +318,7 @@ public abstract partial class ImageFrameCollectionTests
 
             if (aData.ColorTableMode == GifColorTableMode.Local && bData.ColorTableMode == GifColorTableMode.Local)
             {
-                Assert.Equal(aData.DecodedLocalColorTable.Length, bData.DecodedLocalColorTable.Length);
+                Assert.Equal(aData.LocalColorTable.Value.Length, bData.LocalColorTable.Value.Length);
             }
         }
     }

tests/ImageSharp.Tests/Metadata/ImageFrameMetadataTests.cs

@@ -26,14 +26,14 @@ public class ImageFrameMetadataTests
         ImageFrameMetadata metaData = new();
         GifFrameMetadata gifFrameMetadata = metaData.GetGifMetadata();
         gifFrameMetadata.FrameDelay = frameDelay;
-        gifFrameMetadata.DecodedLocalColorTable = Enumerable.Repeat(Color.HotPink, colorTableLength).ToArray();
+        gifFrameMetadata.LocalColorTable = Enumerable.Repeat(Color.HotPink, colorTableLength).ToArray();
         gifFrameMetadata.DisposalMethod = disposalMethod;
 
         ImageFrameMetadata clone = new(metaData);
         GifFrameMetadata cloneGifFrameMetadata = clone.GetGifMetadata();
 
         Assert.Equal(frameDelay, cloneGifFrameMetadata.FrameDelay);
-        Assert.Equal(colorTableLength, cloneGifFrameMetadata.DecodedLocalColorTable.Length);
+        Assert.Equal(colorTableLength, cloneGifFrameMetadata.LocalColorTable.Value.Length);
         Assert.Equal(disposalMethod, cloneGifFrameMetadata.DisposalMethod);
     }
 

tests/ImageSharp.Tests/TestImages.cs

@@ -482,6 +482,8 @@ public static class TestImages
             public const string Issue2288_B = "Gif/issues/issue_2288_2.gif";
             public const string Issue2288_C = "Gif/issues/issue_2288_3.gif";
             public const string Issue2288_D = "Gif/issues/issue_2288_4.gif";
+            public const string Issue2450 = "Gif/issues/issue_2450.gif";
+            public const string Issue2198 = "Gif/issues/issue_2198.gif";
         }
 
         public static readonly string[] All = { Rings, Giphy, Cheers, Trans, Kumin, Leo, Ratio4x1, Ratio1x4 };